Warnings
Warnings issued by DRAINS are now more detailed and emphatic. This is because some users may insert incomplete or ambiguous data, producing doubtful results.
One common problem is the specification of open channels or overflow routes that are too low, and overflow. DRAINS can only extrapolate the line segments at the extremities of a cross-section, which may be incorrect. A warning like the one below stresses the need to define sections more realistically.
Another problem occurs when using the Lite hydraulic model in cases where the surface water level downstream of a pit rises above the ponded water level at the pit, and a reverse flow may occur along the overflow route (this usually coincides with a high flow in a main pipeline that forces water up smaller pipelines). The following message indicates that a problem of this type is occurring.
This is not a problem with the Full unsteady hydraulic model which calculates reverse flows along overflow routes. With the Lite hydraulic model, it will be necessary to adjust pit levels to prevent flow reversals.